1. Field of the Invention
The invention generally relates to a method for sequestration contaminates. More particularly, the invention relates to significant performance enhancement over existing mineral carbonation processes through the use of a high mass transfer system and an efficient pH swing reaction, e.g., a direct and indirect method of sequestering with a gas liquid contactor.
2. Discussion of the Related Art
Fossil fuel combustion, including coal, petroleum and natural gas, supply more than two thirds of our nation's electricity and nearly all of our transportation energy needs. With our expanding economy and national security needs, our reliance on fossil fuels will likely continue for the next two to three decades. Carbon dioxide has been identified as a Green House Gas (GHG) and is implicated in anthropogenic climate warming. In the U.S., CO2 accounts for nearly 95% of energy related emissions and 85% of the GHG inventory. Various approaches to atmospheric CO2 reduction have been proposed and include reducing GHG source emissions through the use of more energy efficient, renewable and alternative fuel systems, and enhancing the economic viability of technologies that capture and store or sequester CO2.
Reduction in the atmospheric concentration of CO2 greenhouse gas can be achieved by capturing CO2 emissions from large industrial sources and permanently storing captured CO2 in some form. For example, permanent storage of captured CO2 can be achieved by injecting pressurized CO2 underground or undersea. Alternatively, CO2 can be converted to calcium carbonate or magnesium carbonate and land filled. With the CO2 injection approach the risks exist that CO2 will escape from the storage site. To mitigate these risks the CO2 storage sites have to be monitored and the resources have to be committed in case a CO2 leak occurs. If the CO2 is converted to solid carbonates, the risks associated with permanent storage are essentially zero, making this approach to permanent CO2 storage more attractive over the underground CO2 storage approach.
Carbon dioxide sequestration is attractive for GHG reduction because it enables the continued use of fossil fuels including coal, petroleum and natural gas, which supply more than two thirds of our nation's electricity and nearly all of our transportation energy needs. With our expanding economy and national security needs, our reliance on fossil fuels will likely continue for the next two to three decades.
The mineral carbonation process is an attractive storage option for CO2 as it offers many advantages over other sequestration approaches. Primarily these are the formation of geologically stable and environmentally benign carbonates which present minimal safety and legacy issues. However, most mineral carbonation processes have been assessed to be uneconomical due to slow dissolution kinetics and unfavorable carbonation energetics. Huijgen, et al., Cost evaluation of CO2 sequestration by aqueous mineral carbonation, Energy Conversion and Management, 48, pp. 1923-1935 (2007), which is hereby incorporated by reference as if fully set forth herein.